CONFIG_AIC7XXX_OLD_CMDS_PER_DEVICE: Maximum number of TCQ commands per device

General informations

The Linux kernel configuration item CONFIG_AIC7XXX_OLD_CMDS_PER_DEVICE:

• prompt: Maximum number of TCQ commands per device
• type: int
• depends on: CONFIG_SCSI_AIC7XXX_OLD
• defined in arch/sparc64/Kconfig
• found in Linux kernels: 2.5.45–2.5.72

Help text

Specify the number of commands you would like to allocate per SCSI device when Tagged Command Queueing (TCQ) is enabled on that device.

Reasonable figures are in the range of 8 to 24 commands per device, but depending on hardware could be increased or decreased from that figure. If the number is too high for any particular device, the driver will automatically compensate usually after only 10 minutes of uptime. It will not hinder performance if some of your devices eventually have their command depth reduced, but is a waste of memory if all of your devices end up reducing this number down to a more reasonable figure.

NOTE: Certain very broken drives are known to lock up when given more commands than they like to deal with. Quantum Fireball drives are the most common in this category. For the Quantum Fireball drives it is suggested to use no more than 8 commands per device.

Default: 8

Hardware

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Sources

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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